Research ArticleMATERIALS SCIENCE

Elastic and electronic tuning of magnetoresistance in MoTe2

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Science Advances  15 Dec 2017:
Vol. 3, no. 12, eaao4949
DOI: 10.1126/sciadv.aao4949
  • Fig. 1 Structure and transport.

    (A) Crystal structure of MoTe2 in the 1T′ phase projected on the ab plane, with the zigzag chains marked running along the b axis. (B) Unit cell of the 1T′ and Td structures projected on the ac plane. (C) Plot of the resistivity, ρ(T), along the b axis with ε||b. The kink around 240 K is evidence of the structural phase transition from the 1T′ to Td phase. (D) Derivative of dρ(T)/dT calculated from (C). (E) Strain dependence of TS1(ε) − TS1(ε = 0) on cooling (left axis) and TS2(ε) − TS2(ε = 0) on warming (right axis). TS1/TS2 are the maximum obtained from the dρ(T)/dT derivative on cooling and warming cycles. (F) Strain dependence of the width of the thermal hysteresis, defined as HW(ε) − HW(0) = [TS2(ε) −εTS1(ε)] − [TS2(ε = 0) − TS1(ε = 0)], with ε applied along a and b directions.

  • Fig. 2 MR under field.

    (A and B) Schematic illustrations of the electric transport measurements with strain along b and a crystallographic directions, respectively. The red arrows indicate the expansion directions for the piezo stack under electric voltage. A ribbon-like MoTe2 single crystal was glued to the surface of a piezo stack and cured so that it can transfer the strain effectively. Four gold wires were attached to the surface of the crystal for the four-probe electric transport measurements. Tensile strain was applied on MoTe2 through a converse piezoelectric effect, which can be controlled by applying electric field on the piezo stack. (C and D) Plots of the in-plane resistivity at 3, 6, and 9 T as a function of strain.

  • Fig. 3 Strain-induced MR.

    (A) Magnetic field dependence of SMR determined at several temperatures and as a function of ε||b. The SMR is negative because the MR is reduced under strain. (B) Magnetic field dependence of SMR determined with ε||a. (C and D) SMR plotted as a function of tensile strain, ε, at 9 T at three different temperatures.

  • Fig. 4 Band structure under strain.

    Band structure comparison of the Td phase of MoTe2 for strains along a (A) and b (B) directions. (C) Corresponding changes of the DOS. Fermi surface cuts at kz = 0 in (D), (E), and (F) for zero strain and 0.5% strains along a and b directions, respectively. The two types of Weyl points are indicated with red and black stars between the electron and hole pockets near the zone center in (D). The color gradient indicates the component ratio of the Mo d orbitals to Te p orbitals around the Fermi surfaces.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/12/eaao4949/DC1

    fig. S1. XRD for MoTe2 single crystal.

    fig. S2. MoTe2 crystal on the piezoelectric stack.

    fig. S3. Transport and SMR data on samples 1 and 2.

    fig. S4. Transport and SMR data on samples 3 and 4.

    fig. S5. Conductivity, carrier density, and mobility with and without strain.

    table S1. The voltage-strain relation of the piezoelectric stack.

    References (3941)

  • Supplementary Materials

    This PDF file includes:

    • fig. S1. XRD for MoTe2 single crystal.
    • fig. S2. MoTe2 crystal on the piezoelectric stack.
    • fig. S3. Transport and SMR data on samples 1 and 2.
    • fig. S4. Transport and SMR data on samples 3 and 4.
    • fig. S5. Conductivity, carrier density, and mobility with and without strain.
    • table S1. The voltage-strain relation of the piezoelectric stack.
    • References (39–41)

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